Structural defence is coupled with the leaf economic spectrum across saplings of spiny species

Abstract

Given that the rate of resource capture constrains plant growth and defence, understanding the linkage between the leaf economic spectrum (LES) and defence and how it contributes to growth is central to predicting species performance. In spite of the prevalence of spiny plants in many plant communities, little is known about how the LES relates to defence and growth rate across these species. We grew 42 spiny species, from diverse environments, under common garden conditions for 15 weeks and measured LES (leaf N, SLA and assimilation rate), defence and growth traits. We assessed general relationships between LES and growth rate and tested whether structural defences (spines, leaf fibre and lignin content) and quantitative chemical defences (condensed tannins) are linked to the LES and growth and if different spine types (i.e. leaf spines, stipular spines, prickles and thorns), with distinct anatomical origins, partition out across the LES. We observed two independent trait axes that together explained ~68% of trait variation across species. The first axis showed that structural defences (spines, leaf fibre and lignin content) trade off with leaf productivity along the LES. Axis 2 revealed that condensed tannins is orthogonal and less integrated with the LES‐structural defence axis. Bivariate trait analyses disclosed positive covariations between LES traits and sapling growth rate. All structural defence traits were negatively related to sapling growth. Across spine types, species with leaf spines were associated with the conservative end of the LES, characterized by high structural defences and lower leaf productivity relative to other spine types. Synthesis: Our study shows that the LES and structural defences are coupled in spiny species such that constitutive growth – defence strategies range from fast‐growing species with low allocation to defences to slow‐growing species that invest heavily in structural defences (dominated by leaf spiny species).

Intraspecific Variation In Plant Economic Traits Predicts Trembling Aspen Resistance To A Generalist Insect Herbivore

“…Similarly, across species of spiny plants, physical defenses are associated with leaf productivity, whereas chemical defenses are not (Armani et al 2020). Both chemical and physical defense traits are correlated with LES traits within Asclepias syriaca, but not among different Asclepias species (Agrawal 2020).…”

Evolving the structure: climatic and developmental constraints on the evolution of plant architecture. A case study in Euphorbia

“…This point can be exemplified by the presence of spines in many species of Euphorbia . Spines are thought to predominantly function as a defence against vertebrate herbivores (Cooper & Owen‐Smith, 1986; Burns, 2014; Wigley et al ., 2015; Charles‐Dominique et al ., 2016; Tomlinson et al ., 2016; Armani et al ., 2020). The latter is identified as a neutral trait in our analysis, indicating that it is not aligned with the climate groups we tested here.…”

Plant Chemistry Determines Host Preference and Performance of an Invasive Insect

“…Plant anti-herbivore secondary metabolites (i.e., phenolics) and plant structural components (i.e., cellulose and lignin) are important in affecting insect development. For example, lignin, as an important predictor of leaf toughness, can decrease arthropod damage, even at relatively low amounts ( Ohmart and Edwards, 1991 ; Steinbauer et al, 1998 ; Armani et al, 2020 ). Our results indicated that lignin content is a significant defense strategy, suggesting that potato tuberworm larvae develop better in S. tuberosum plants with low lignin, but worse in L. barbarum with high lignin.…”